Shadow of the โก่งคิ้ว gong khiw (eyebrow-shaped pediment?) on the main door:
At his feet:
A few butterflies around him (no idea what they signify), & above him, one of two eagles seizing a snake that has caught a frog in its mouth:
Prince Siddhartha saw the snake catch the frog, & as the two were still struggling, an eagle swooped down & seized the snake, which was still hanging onto the frog - reflecting on this the prince realised how life is an endless cycle of the stronger preying on the weaker for survival - an endless cycle of suffering. This event would be followed by the 'four sights' & the prince's eventual decision to become a monk.
Right panel (no idea what's going on here):